KFunk Posted February 16, 2009 Share Posted February 16, 2009 How do I get the needle jet out of this '81 xs400 carb? I took out the main jet and the washer underneath, and I see the hollow needle jet and there's a little open tab on the side, and its too narrow to get a screwdriver in it. The Haynes manual just says to push the needle jet out, and doesn't give any specifics. It seems like its pretty tight in there. I just want to clean out any crud in it, while I have things apart. I was runnin around on it today, and it started runnin like crap, acted like it was down a cylinder, then would die and eventually didn't restart at all. I pushed it on home. It'd fire and run for a bit with starter fluid, and the fuel strainer was recently cleaned off, so yep its time to tear down the carbs. This bike only has 2000 miles on it, so its been sittin and rusting a long, long time. Both pilot jets look clogged up, but I think the main problem was a float needle valve was stuck shut. I can force it in and out by hand...but its stiff and clicks. any idea how I can smooth up its motion? It should run awesome as soon as I get stuff cleaned up and back together. I just put the new brake shoes in it yesterday (yes the pad material came off the shoes, and I ended up takin an angle grinder to hack up the spacer just to get the axle out.) I also replaced the footrest bushings yesterday, and it feels great to have a solid footing. I had been missing the washers on the inside too, so that made it really floppy. Link to comment Share on other sites More sharing options...
KFunk Posted February 16, 2009 Author Share Posted February 16, 2009 Nevermind, I got 'em out. Just did some lookin and that section was covered earlier in the Haynes manual, but still kinda confusing. I figured out they could only come out thru the carb throat, got brave and gave 'em a few whacks with the hammer and a screwdriver and they broke free. They sure are nasty looking. I'm gonna soak them over night in something, think brake cleaner is OK? Oh, and on the float needles, it appeared the problem was some weird ridges around the edge preventing it from sliding. I filed them down and polished them off with really fine grade steel wool, and they seem to operate smooth. I still gotta find my ruler to set the float height, and she should be running sweet tomorrow evening. Link to comment Share on other sites More sharing options...
Moderator drewpy Posted February 16, 2009 Moderator Share Posted February 16, 2009 Nevermind, I got 'em out. Just did some lookin and that section was covered earlier in the Haynes manual, but still kinda confusing. I figured out they could only come out thru the carb throat, got brave and gave 'em a few whacks with the hammer and a screwdriver and they broke free. They sure are nasty looking. I'm gonna soak them over night in something, think brake cleaner is OK? you can get carb cleaner, although if its out, any solvent should move the petrol gunk. don't forget to use compressed air and no poking with wires!! they weld themselves in cause the ally corrodes and expands differently than the brass. Link to comment Share on other sites More sharing options...
KFunk Posted February 16, 2009 Author Share Posted February 16, 2009 OK, I found some compressed air and cleaned out all passages. Is there supposed to be a hole in the tip of the pilot jet? looks like there might be one in one of them, but not the other... Anyways, I'm a little confused on setting the float height. Do you set it at the position where the float bowl would be full or empty? If I just turn the carbs upside down like in the manual, then gravity makes the floats sink all the down well below the specified height, and the adjustment tang wouldn't help the position it since its sticking up vertically. I assume they must mean the other position, as if you're picking up on the floats to their max height, or if the carbs are sitting right side up and hanging down to their resting position. Just wanna double-check before I put 'em back together. Link to comment Share on other sites More sharing options...
Moderator drewpy Posted February 16, 2009 Moderator Share Posted February 16, 2009 OK, I found some compressed air and cleaned out all passages. Is there supposed to be a hole in the tip of the pilot jet? looks like there might be one in one of them, but not the other... not quite sure what you mean by that!! Anyways, I'm a little confused on setting the float height. Do you set it at the position where the float bowl would be full or empty? If I just turn the carbs upside down like in the manual, then gravity makes the floats sink all the down well below the specified height, and the adjustment tang wouldn't help the position it since its sticking up vertically. I assume they must mean the other position, as if you're picking up on the floats to their max height, or if the carbs are sitting right side up and hanging down to their resting position. Just wanna double-check before I put 'em back together. floats are checked when the fuel is being stopped by the needle valve. so its neither fully resting or fully down. I blow gently down the inlet and close the float. When the air stops thats when you take the measurement drewps Link to comment Share on other sites More sharing options...
KFunk Posted February 17, 2009 Author Share Posted February 17, 2009 not quite sure what you mean by that!! floats are checked when the fuel is being stopped by the needle valve. so its neither fully resting or fully down. I blow gently down the inlet and close the float. When the air stops thats when you take the measurement drewps OK, I went ahead and did it that way... put it back together.. and it still doesn't want to go for some reason. I put it on prime for a bit and cranked and cranked, and nothing. I tried some starting fluid in the right cylinder, and managed to get it to fire a bit but it wouldnt stay running. Tried left, not so much good. Seems to be fuel coming down from the petcock OK. I dunno... I'll try to fiddle with it some tomorrow evening. Link to comment Share on other sites More sharing options...
KFunk Posted February 17, 2009 Author Share Posted February 17, 2009 i'm thinkin i might just have it set a lot leaner than before... and should try richening it up. I stupidly took out the mixture screws all the way without taking note of how many turns out they were. Then I just checked the manual that said 1 to 1 1/4 turns out, and put them both in at about 1 1/8 turns out. I'm thinkin i should take them both out a turn or two, fire it up hopefully, and adjust from there. It's all stock, but the air filters are kinda burnt up and essentially non existent, so that may be giving it too much air. Oh and I might as well check valve clearances for the heck of it. Link to comment Share on other sites More sharing options...
Moderator drewpy Posted February 17, 2009 Moderator Share Posted February 17, 2009 i'm thinkin i might just have it set a lot leaner than before... and should try richening it up. I stupidly took out the mixture screws all the way without taking note of how many turns out they were. Then I just checked the manual that said 1 to 1 1/4 turns out, and put them both in at about 1 1/8 turns out. I'm thinkin i should take them both out a turn or two, fire it up hopefully, and adjust from there. It's all stock, but the air filters are kinda burnt up and essentially non existent, so that may be giving it too much air. Oh and I might as well check valve clearances for the heck of it. turning out will richen them Link to comment Share on other sites More sharing options...
pbaszxs400 Posted February 17, 2009 Share Posted February 17, 2009 Once I get everything to were I think it should be, I usually put clear fuel line onto the bowl drains and use those as my level to make sure the fuel level in the bowls is not too high/ low. Link to comment Share on other sites More sharing options...
KFunk Posted February 17, 2009 Author Share Posted February 17, 2009 Thanks again for all the help, you're providing way more info than the manual. It'd take me forever to figure it out without you. I just checked the valve clearances for the heck of it, and all seem ok with no adjustments necessary. Not as easy to check as my old BMW car, but do-able. Next I want to check out the breakers to see 'em, but I can't figure out how to get out the little plug that goes over one of the phillips head screws that holds the breaker cover in. Looks like I'm gonna have to get a drill, but is there something I'm missing? Sorry for all the newbie-ness, but I can't seem to find much of the info I want thru the search. Link to comment Share on other sites More sharing options...
KFunk Posted February 18, 2009 Author Share Posted February 18, 2009 and woohooo, it fires up and runs again. Sounds pretty sweet and free revvin with the carbs cleaned out. It takes some starter fluid to get it goin, and it won't idle yet though, gotta find the sweet spot in the mixture screws I think, and find a screwdriver small enough to adjust them with the gas tank still on there. Link to comment Share on other sites More sharing options...
Moderator drewpy Posted February 18, 2009 Moderator Share Posted February 18, 2009 Thanks again for all the help, you're providing way more info than the manual. It'd take me forever to figure it out without you. I just checked the valve clearances for the heck of it, and all seem ok with no adjustments necessary. Not as easy to check as my old BMW car, but do-able. Next I want to check out the breakers to see 'em, but I can't figure out how to get out the little plug that goes over one of the phillips head screws that holds the breaker cover in. Looks like I'm gonna have to get a drill, but is there something I'm missing? Sorry for all the newbie-ness, but I can't seem to find much of the info I want thru the search. yep, its a drill job, so you have electronic ignition. nothing to adjust as it a trigger Link to comment Share on other sites More sharing options...
KFunk Posted February 18, 2009 Author Share Posted February 18, 2009 yep, its a drill job, so you have electronic ignition. nothing to adjust as it a trigger Ohhh OK, I figured so. So the older bikes with points didn't have the plug? That saves me some trouble I guess, till the module or whatever dies... I kinda like points tho in their simplicity to see visually and cost of replacing them. I had wondered when the changeover happened, as my '83 rx50 doesn't have point. I'm still running points in my '74 BMW car tho. Link to comment Share on other sites More sharing options...
KFunk Posted February 19, 2009 Author Share Posted February 19, 2009 This is gettin annoying trying to figure out how to get the thing to idle. I keep goin back and forth on the mixture screws, and checkin the plugs, and can't get it right. Sometimes it'll start up easy, sometimes it requires some starter fluid. It'll rev up pretty damn high for a while, but will stumble and die if I let off the gas. Should be a dark tan on the plugs, right? Link to comment Share on other sites More sharing options...
KFunk Posted February 19, 2009 Author Share Posted February 19, 2009 OK, I got a couple ideas. I could switch and put hotter plugs in to make it run easier. I've got NGK BP5ES and BP6ES standing by, since luckily it takes the same plugs as my BMW car. I also might crank the idle speed way up. Whatever it takes to get it to some kinda of idle, even if really high. Then I'll tune the mixture of each carb by ear till its runs the fastest/smoothest, crank down the idle, fine tune it again, and so on till I get it to 1200 rpm idle and I can use the stock BP7ES plugs. The only other thing I could suspect is the float level, since I messed with it a lot. But that seems like a pretty darn simple and reliable way of checking it, drewpy. It should be around 32mm right? Thats whats in my Haynes manual, hope I got that right. I'll give it another shot tonight, and hopefully get it to go good before pissing the neighbors off too much. Link to comment Share on other sites More sharing options...
pbaszxs400 Posted February 19, 2009 Share Posted February 19, 2009 It sounds an awful lot like your float height (provided everything else is clean and leak free). The reason that it runs at a high rev is becuse you are "pulling harder" through the carbs, and are able to pull fuel from lower in the bowl. On mine I put a clear tube on the fuel drain outlet at the bottom of the bowl, and loosen the drain screw. If you hold the other end of the tube higher than the carb, you will see exactly how high the fuel is filling the bowls. I usually drain the bowls, then do the tube measurement. This eliminates any error from fuel getting past a drippy needle. Link to comment Share on other sites More sharing options...
KFunk Posted February 19, 2009 Author Share Posted February 19, 2009 It sounds an awful lot like your float height (provided everything else is clean and leak free). The reason that it runs at a high rev is becuse you are "pulling harder" through the carbs, and are able to pull fuel from lower in the bowl. On mine I put a clear tube on the fuel drain outlet at the bottom of the bowl, and loosen the drain screw. If you hold the other end of the tube higher than the carb, you will see exactly how high the fuel is filling the bowls. I usually drain the bowls, then do the tube measurement. This eliminates any error from fuel getting past a drippy needle. Yeah, I was thinking about trying that like you said, but I wasn't sure how to connect the tube. I just have phillips head screws at the bottom flush with the surface. It seems like I'd need a nipple with the right threads that would thread in there. Or are you just screwing a soft rubber hose in there thats a close enough fit? Link to comment Share on other sites More sharing options...
Moderator drewpy Posted February 19, 2009 Moderator Share Posted February 19, 2009 Yeah, I was thinking about trying that like you said, but I wasn't sure how to connect the tube. I just have phillips head screws at the bottom flush with the surface. It seems like I'd need a nipple with the right threads that would thread in there. Or are you just screwing a soft rubber hose in there thats a close enough fit? the tube method is the best as it takes into account the vagrates of each carb. why not get a matching bolt and drill/tap for a nipple? Link to comment Share on other sites More sharing options...
KFunk Posted February 20, 2009 Author Share Posted February 20, 2009 the tube method is the best as it takes into account the vagrates of each carb. why not get a matching bolt and drill/tap for a nipple? i'll see what i can do tomorrow... gotta find a drill and such. quick question on the floats: About the center tabs in the middle, where the needle valve actually rests. Should that be straight across, like on the same plane as the bracket of the float? or should it be bent down away from the needle valve slightly? One of mine was one way and one was the other.... I bent the flat one down to match the other, since it seemed to give the float more room to move. Maybe that was the wrong thing.... Link to comment Share on other sites More sharing options...
Moderator drewpy Posted February 20, 2009 Moderator Share Posted February 20, 2009 i'll see what i can do tomorrow... gotta find a drill and such. quick question on the floats: About the center tabs in the middle, where the needle valve actually rests. Should that be straight across, like on the same plane as the bracket of the float? or should it be bent down away from the needle valve slightly? One of mine was one way and one was the other.... I bent the flat one down to match the other, since it seemed to give the float more room to move. Maybe that was the wrong thing.... thats how you change the float height!! keep moving them and they will snap off eventually!! Link to comment Share on other sites More sharing options...
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